2. Construction: Earthworks

earthworks

excavation, movement, deposition, compaction of earth in order to change the physical nature & shape of the terrain

earthworks objectives

to change the shape of local terrain

earthworks

canals, roadways/highways, railways, runways, dams, ports, pipelines

fill

embankments

cut

excavations

balance

quantity of material we excavate [cut] should be as close as possible to quantity of material we deposit [fill], disposal of material is very expensive

borrow pit

excavate ground for soil → pay farmer/landowner material rights

earthworks planning

very expensive, plant intensive, subject to seasons & weather

haul length

cost is proportional to

Mass Haul Optimisation

process of planning the movement of excavated material across a site to minimise the cost, time, and environmental impact of the project

positive

in mass haul diagram, fill is

excavation, movement, deposition and compaction

earthworks operations

deposition and compaction

material is spread out into thin layers

compacted [earthworks compactors, or towed roller]

compactor

self propelled vehicle, one of its wheels are drums

smooth or sheepsfoot

static or vibrating

roller

towed by bulldozer

can be used w/o roller for spreading and trimming

excavator + dumptruck, scraper

two methods for excavation and movement

excavator + dumptruck

common, versatile, economic

excavator digs out material and deposits into back of dumptruck

time taken for truck to complete cycle determines # of trucks

length of cycle depends on length of haul road, size of truck, speed of truck, rate at which excavator can work

scraper

scrapes ground as moves along, automatically depositing material into its skip

drive to deposit area and repeat in opposite direction while moving along

expensive due to plant and fuel used

excavator plant

excavators, bulldozers, articulated dump trucks, rigid dump trucks, scrapers, ancillary plant: compactors and graders

plant operator

high skilled operator very valuable to a project

ganger

directs individual activities (excavation or deposition activity)

ensures shape and size of earthworks is correct

link between management and plant operators

materials in earthworks

ideally no extra material required

realistically imported material needed

1. acceptable fill in embankments

2. rock blankets

3. structural backfill

4. capping

5. top soiling